1. Field of the Invention
The present invention relates to a signal processing apparatus and method thereof, and more particularly, to a signal processing apparatus and method for an optical disc drive.
2. Description of the Prior Art
In an optical disc drive, the photo diode signals sensed by the reflected light reflected from an optical disc are usually processed in analog domain for generating servo error signals. The servo controller utilizes the servo error signals to control the spindle motor, the optical pickup, sled motor, and so on.
Before the analog photo diode signals are processed into analog servo error signals, the analog photo diode signals should be adjusted by amplification, offset compensation, and filtering, and then be processed. However, since generating servo signals are executed in analog domain, the components required for the above actions are complicated and expensive.
On another aspect, when the optical disc drive executes different actions such as writing and reading, the power of the laser diode differs in different conditions. That is, when the optical disc drive is reading, the power of the laser beam is controlled in a constant manner, and when the optical disc drive is writing, the power of the laser beam is differed according to the different write strategy. In this way, when the optical disc drive is writing, the photo diode signals possibly generate wrong or bad servo error signals.